Experimental investigations on residual bond performance in concrete subjected to elevated temperature

In this work, the residual bond performance of reinforcement in concrete under elevated temperatures is experimentally investigated using the cuboidal (square prismatic) concrete specimens. The test reinforcement was placed at different cover distances with an aim to study the influence of elevated temperature on bond pullout and bond splitting behavior. It was found that under ambient conditions as well as after exposure to elevated temperature, concrete cover has a strong influence on the absolute value of the bond strength and failure mode. The thermal degradation of bond strength is found to be similar to that of compressive or tensile strength of concrete for pure bond or splitting failure respectively. The level of confinement provided by the concrete cover to the rebar reduces with increasing temperature, while the width of splitting cracks increases with increasing temperature. The bond stiffness gradually reduces with the increase in exposure temperature for both pullout and splitting failure. The details and the results of the experimental investigations are reported in this paper.